Technical Field
The present disclosure relates to an optical lens system, imaging device and electronic device. More particularly, the present disclosure relates to a compact optical lens system and imaging device applicable to an electronic device.
Description of Related Art
In recent years, with the popularity of electronic devices having camera functionalities, the demand of miniaturized optical systems has been increasing. The sensor of a conventional optical system is typically a CCD (Charge-Coupled Device) or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor. As the advanced semiconductor manufacturing technologies have allowed the pixel size of image sensors to be reduced and compact, optical systems have gradually evolved toward the field of higher megapixels, there is an increasing demand for compact optical systems featuring better image quality.
A conventional compact optical system in a portable electronic product typically utilizes a three-element lens structure. Due to the popularity of electronic products with high-end specifications, such as smart TVs, wireless monitoring devices, motion sensing input devices and other high-end electronic devices, the requirements for high resolution and image quality of present compact optical systems increase significantly. However, the conventional optical systems cannot satisfy these requirements of the compact optical systems.
Another conventional compact optical system provides a four-element lens structure. When the first lens element of the optical system cannot provide sufficient refractive power with higher refractive power distributed among the second, third and fourth lens elements, it is not favorable for correcting peripheral aberrations within the optical system, expanding the surrounding light cone size, and improving the peripheral resolution and relative illumination. Especially when the image-side surface of the fourth lens element is concave, the incident angle of the off axis light with respect to the image sensor cannot be effectively suppressed, which reduces the responding efficiency of the image sensor and is not suitable for infrared optical system.